From 4093325f829746b88eaf02a5ae3b88a325ea8b75 Mon Sep 17 00:00:00 2001 From: Namhyung Kim Date: Tue, 30 Dec 2014 17:47:47 +0900 Subject: [PATCH] perf probe: Fix crash in dwarf_getcfi_elf David reported that perf can segfault when adding an uprobe event like this: $ perf probe -x /lib64/libc-2.14.90.so -a 'malloc size=%di' (gdb) bt #0 parse_eh_frame_hdr (hdr=0x0, hdr_size=2596, hdr_vaddr=71788, ehdr=0x7fffffffd390, eh_frame_vaddr= 0x7fffffffd378, table_entries=0x8808d8, table_encoding=0x8808e0 "") at dwarf_getcfi_elf.c:79 #1 0x000000385f81615a in getcfi_scn_eh_frame (hdr_vaddr=71788, hdr_scn=0x8839b0, shdr=0x7fffffffd2f0, scn=, ehdr=0x7fffffffd390, elf=0x882b30) at dwarf_getcfi_elf.c:231 #2 getcfi_shdr (ehdr=0x7fffffffd390, elf=0x882b30) at dwarf_getcfi_elf.c:283 #3 dwarf_getcfi_elf (elf=0x882b30) at dwarf_getcfi_elf.c:309 #4 0x00000000004d5bac in debuginfo__find_probes (pf=0x7fffffffd4f0, dbg=Unhandled dwarf expression opcode 0xfa) at util/probe-finder.c:993 #5 0x00000000004d634a in debuginfo__find_trace_events (dbg=0x880840, pev=, tevs=0x880f88, max_tevs=) at util/probe-finder.c:1200 #6 0x00000000004aed6b in try_to_find_probe_trace_events (target=0x881b20 "/lib64/libpthread-2.14.90.so", max_tevs=128, tevs=0x880f88, pev=0x859b30) at util/probe-event.c:482 #7 convert_to_probe_trace_events (target=0x881b20 "/lib64/libpthread-2.14.90.so", max_tevs=128, tevs=0x880f88, pev=0x859b30) at util/probe-event.c:2356 #8 add_perf_probe_events (pevs=, npevs=1, max_tevs=128, target=0x881b20 "/lib64/libpthread-2.14.90.so", force_add=false) at util/probe-event.c:2391 #9 0x000000000044014f in __cmd_probe (argc=, argv=0x7fffffffe2f0, prefix=Unhandled dwarf expression opcode 0xfa) at at builtin-probe.c:488 #10 0x0000000000440313 in cmd_probe (argc=5, argv=0x7fffffffe2f0, prefix=) at builtin-probe.c:506 #11 0x000000000041d133 in run_builtin (p=0x805680, argc=5, argv=0x7fffffffe2f0) at perf.c:341 #12 0x000000000041c8b2 in handle_internal_command (argv=, argc=) at perf.c:400 #13 run_argv (argv=, argcp=) at perf.c:444 #14 main (argc=5, argv=0x7fffffffe2f0) at perf.c:559 And I found a related commit (5704c8c4fa71 "getcfi_scn_eh_frame: Don't crash and burn when .eh_frame bits aren't there.") in elfutils that can lead to a unexpected crash like this. To safely use the function, it needs to check the .eh_frame section is a PROGBITS type. Reported-by: David Ahern Tested-by: David Ahern Signed-off-by: Namhyung Kim Acked-by: Masami Hiramatsu Cc: David Ahern Cc: Mark Wielaard Cc: Masami Hiramatsu Link: http://lkml.kernel.org/r/20141230090533.GH6081@sejong Signed-off-by: Arnaldo Carvalho de Melo --- tools/perf/util/probe-finder.c | 18 +++++++++++++++++- 1 file changed, 17 insertions(+), 1 deletion(-) diff --git a/tools/perf/util/probe-finder.c b/tools/perf/util/probe-finder.c index c7918f83b300..b5247d777f0e 100644 --- a/tools/perf/util/probe-finder.c +++ b/tools/perf/util/probe-finder.c @@ -989,8 +989,24 @@ static int debuginfo__find_probes(struct debuginfo *dbg, int ret = 0; #if _ELFUTILS_PREREQ(0, 142) + Elf *elf; + GElf_Ehdr ehdr; + GElf_Shdr shdr; + /* Get the call frame information from this dwarf */ - pf->cfi = dwarf_getcfi_elf(dwarf_getelf(dbg->dbg)); + elf = dwarf_getelf(dbg->dbg); + if (elf == NULL) + return -EINVAL; + + if (gelf_getehdr(elf, &ehdr) == NULL) + return -EINVAL; + + if (elf_section_by_name(elf, &ehdr, &shdr, ".eh_frame", NULL) && + shdr.sh_type == SHT_PROGBITS) { + pf->cfi = dwarf_getcfi_elf(elf); + } else { + pf->cfi = dwarf_getcfi(dbg->dbg); + } #endif off = 0; -- 2.20.1